{
  "id": 62376,
  "title": "84% of empty pictures in LB",
  "url": "/competitions/airbus-ship-detection/discussion/62376",
  "author_name": "Max",
  "post_date": "2018-07-31T21:02:18.194000",
  "votes": 39,
  "comment_count": 11,
  "views": 0,
  "content": "<p>An empty submission gives you a score of 0.847.</p>\n\n<p>If my understanding is right and the metric equivalent to the TGS competition where a correct empty mask is 1 and an incorrect not empty mask is 0, we are in for a huge Public / Private LB shake up. \nCorrectly predicting empty masks has a huge importance here</p>",
  "messages": [
    {
      "id": 364609,
      "postDate": "2018-07-31T21:02:18.193Z",
      "content": "<p>An empty submission gives you a score of 0.847.</p>\n\n<p>If my understanding is right and the metric equivalent to the TGS competition where a correct empty mask is 1 and an incorrect not empty mask is 0, we are in for a huge Public / Private LB shake up. \nCorrectly predicting empty masks has a huge importance here</p>",
      "rawMarkdown": "An empty submission gives you a score of 0.847.\n\nIf my understanding is right and the metric equivalent to the TGS competition where a correct empty mask is 1 and an incorrect not empty mask is 0, we are in for a huge Public / Private LB shake up. \nCorrectly predicting empty masks has a huge importance here",
      "votes": 39
    },
    {
      "id": 367205,
      "postDate": "2018-08-07T09:57:56.483Z",
      "content": "<p>It is indeed really strange. With an empty submission we should have 0 True Positive (TP) but many False Negatives (FN). So F2 scores are 0 (it doesn't depend on the threshold). So the final score, which is an average of the F2 scores should be 0. Did I miss something?</p>",
      "rawMarkdown": "It is indeed really strange. With an empty submission we should have 0 True Positive (TP) but many False Negatives (FN). So F2 scores are 0 (it doesn't depend on the threshold). So the final score, which is an average of the F2 scores should be 0. Did I miss something?",
      "votes": 1,
      "replies": [
        {
          "id": 367213,
          "postDate": "2018-08-07T10:28:23.860Z",
          "content": "<p>Hi, for an empty submission and empty image (with no ships) you have 0 TP, 0 FN and 0 FP. So F2 is 0/0. I think for this case (perfect prediction for an empty image) F2 is just equal to 1. For all images with ships on them you have F2 equal to 0, because you have 0 TP and some FN. That's why we know, that 84% of test images are empty.<br>\nAnd here comes my question to organizers <a href=\"/inversion\">@inversion</a>, <a href=\"/jeffaudi\">@jeffaudi</a>:<br>\nIs it the case for the rest of test set (test set for private LB)? Our training might be different if we knew, that many of the images are empty.</p>",
          "rawMarkdown": "Hi, for an empty submission and empty image (with no ships) you have 0 TP, 0 FN and 0 FP. So F2 is 0/0. I think for this case (perfect prediction for an empty image) F2 is just equal to 1. For all images with ships on them you have F2 equal to 0, because you have 0 TP and some FN. That's why we know, that 84% of test images are empty.<br>\nAnd here comes my question to organizers @inversion, @jeffaudi:<br>\nIs it the case for the rest of test set (test set for private LB)? Our training might be different if we knew, that many of the images are empty.",
          "votes": 6
        },
        {
          "id": 367258,
          "postDate": "2018-08-07T11:45:59.667Z",
          "content": "<p>Thanks for the explanations :) !</p>",
          "rawMarkdown": "Thanks for the explanations :) !"
        }
      ]
    },
    {
      "id": 365920,
      "postDate": "2018-08-03T16:44:41.477Z",
      "content": "<p>Haha, was wondering why everyone had a 84% LB :D</p>",
      "rawMarkdown": "Haha, was wondering why everyone had a 84% LB :D",
      "votes": 1
    },
    {
      "id": 364930,
      "postDate": "2018-08-01T15:17:13.530Z",
      "content": "<p>I thought it is union over intersection? so 0 / 0 = 1?</p>",
      "rawMarkdown": "I thought it is union over intersection? so 0 / 0 = 1?",
      "votes": 2,
      "replies": [
        {
          "id": 365960,
          "postDate": "2018-08-03T18:36:06.783Z",
          "content": "<p>Please, delete the comment with 0 division.</p>",
          "rawMarkdown": "Please, delete the comment with 0 division.",
          "votes": 2
        },
        {
          "id": 371975,
          "postDate": "2018-08-18T01:01:43.153Z",
          "content": "<p>what is the reason to delete the comment with 0 division ? Just curious :D</p>",
          "rawMarkdown": "what is the reason to delete the comment with 0 division ? Just curious :D"
        },
        {
          "id": 372297,
          "postDate": "2018-08-18T21:57:08.330Z",
          "content": "<p><img src=\"https://themathbehindthemagic.files.wordpress.com/2014/03/divide-by-zero1.jpg\" alt=\"ximage\"></p>",
          "rawMarkdown": "![ximage][1]\n\n\n  [1]: https://themathbehindthemagic.files.wordpress.com/2014/03/divide-by-zero1.jpg"
        }
      ]
    },
    {
      "id": 364857,
      "postDate": "2018-08-01T11:32:45.870Z",
      "content": "<p>That's make sense, since ocean are mostly empty.</p>",
      "rawMarkdown": "That's make sense, since ocean are mostly empty.",
      "votes": 2
    },
    {
      "id": 365178,
      "postDate": "2018-08-02T03:27:54.617Z",
      "content": "<p>What does LB stands for? Learning Base?</p>\n\n<p>Ah It was Leader Board</p>",
      "rawMarkdown": "What does LB stands for? Learning Base?\n\nAh It was Leader Board"
    },
    {
      "id": 364973,
      "postDate": "2018-08-01T16:18:42.853Z",
      "rawMarkdown": "",
      "isDeleted": true
    }
  ],
  "comments": [
    {
      "id": 367205,
      "author_name": "Collas Antoine",
      "author_url": "",
      "post_date": "2018-08-07T09:57:56.483000",
      "content": "<p>It is indeed really strange. With an empty submission we should have 0 True Positive (TP) but many False Negatives (FN). So F2 scores are 0 (it doesn't depend on the threshold). So the final score, which is an average of the F2 scores should be 0. Did I miss something?</p>",
      "votes": 1,
      "replies": [
        {
          "id": 367213,
          "author_name": "dzem90",
          "author_url": "",
          "post_date": "2018-08-07T10:28:23.860000",
          "content": "<p>Hi, for an empty submission and empty image (with no ships) you have 0 TP, 0 FN and 0 FP. So F2 is 0/0. I think for this case (perfect prediction for an empty image) F2 is just equal to 1. For all images with ships on them you have F2 equal to 0, because you have 0 TP and some FN. That's why we know, that 84% of test images are empty.<br>\nAnd here comes my question to organizers <a href=\"/inversion\">@inversion</a>, <a href=\"/jeffaudi\">@jeffaudi</a>:<br>\nIs it the case for the rest of test set (test set for private LB)? Our training might be different if we knew, that many of the images are empty.</p>",
          "votes": 6,
          "replies": []
        },
        {
          "id": 367258,
          "author_name": "Collas Antoine",
          "author_url": "",
          "post_date": "2018-08-07T11:45:59.667000",
          "content": "<p>Thanks for the explanations :) !</p>",
          "votes": 0,
          "replies": []
        }
      ]
    },
    {
      "id": 365920,
      "author_name": "Mukesh",
      "author_url": "",
      "post_date": "2018-08-03T16:44:41.477000",
      "content": "<p>Haha, was wondering why everyone had a 84% LB :D</p>",
      "votes": 1,
      "replies": []
    },
    {
      "id": 364930,
      "author_name": "Shawn Shan",
      "author_url": "",
      "post_date": "2018-08-01T15:17:13.530000",
      "content": "<p>I thought it is union over intersection? so 0 / 0 = 1?</p>",
      "votes": 2,
      "replies": [
        {
          "id": 365960,
          "author_name": "Adams",
          "author_url": "",
          "post_date": "2018-08-03T18:36:06.783000",
          "content": "<p>Please, delete the comment with 0 division.</p>",
          "votes": 2,
          "replies": []
        },
        {
          "id": 371975,
          "author_name": "",
          "author_url": "",
          "post_date": "2018-08-18T01:01:43.153000",
          "content": "<p>what is the reason to delete the comment with 0 division ? Just curious :D</p>",
          "votes": 0,
          "replies": []
        },
        {
          "id": 372297,
          "author_name": "Miha Skalic",
          "author_url": "",
          "post_date": "2018-08-18T21:57:08.330000",
          "content": "<p><img src=\"https://themathbehindthemagic.files.wordpress.com/2014/03/divide-by-zero1.jpg\" alt=\"ximage\"></p>",
          "votes": 0,
          "replies": []
        }
      ]
    },
    {
      "id": 364857,
      "author_name": "Ivan Achlaqullah",
      "author_url": "",
      "post_date": "2018-08-01T11:32:45.870000",
      "content": "<p>That's make sense, since ocean are mostly empty.</p>",
      "votes": 2,
      "replies": []
    },
    {
      "id": 365178,
      "author_name": "이햇살(Winbaram)",
      "author_url": "",
      "post_date": "2018-08-02T03:27:54.617000",
      "content": "<p>What does LB stands for? Learning Base?</p>\n\n<p>Ah It was Leader Board</p>",
      "votes": 0,
      "replies": []
    },
    {
      "id": 364973,
      "author_name": "",
      "author_url": "",
      "post_date": "2018-08-01T16:18:42.853000",
      "content": "",
      "votes": 0,
      "replies": []
    }
  ],
  "raw_markdown_by_id": {
    "364609": "An empty submission gives you a score of 0.847.\n\nIf my understanding is right and the metric equivalent to the TGS competition where a correct empty mask is 1 and an incorrect not empty mask is 0, we are in for a huge Public / Private LB shake up. \nCorrectly predicting empty masks has a huge importance here",
    "367205": "It is indeed really strange. With an empty submission we should have 0 True Positive (TP) but many False Negatives (FN). So F2 scores are 0 (it doesn't depend on the threshold). So the final score, which is an average of the F2 scores should be 0. Did I miss something?",
    "365920": "Haha, was wondering why everyone had a 84% LB :D",
    "364930": "I thought it is union over intersection? so 0 / 0 = 1?",
    "364857": "That's make sense, since ocean are mostly empty.",
    "365178": "What does LB stands for? Learning Base?\n\nAh It was Leader Board",
    "364973": ""
  }
}